The Targum understands “sword” and “bow” as metaphors for prayer. Rabbi Joseph B. Soloveitchik tells us that a sword is used for fighting up close; that corresponds to prayers for one’s own immediate needs. A bow is used for fighting at a great distance; that corresponds to prayers for the nation’s long-term well-being. (From The First Blessing of the Day, cited in the Mesoras HaRav Chumash.)